The defendants “cynically thwarted” authorities such as the Food Standards Agency and Interpol that tried to close down their operations, the court heard.

Describing DNP and its effects, Mr Barraclough said it was a “highly toxic substance when ingested, inhaled or absorbed through the skin”.

‘Psychologically addicted’

He added it causes weight loss by burning fat and carbohydrates, in turn causing energy to be converted into heat.

“The result is that that person’s temperature and metabolic rate all dangerously increase,” Mr Barraclough explained.

In the weeks before her death Miss Parry, who had a history of self-harming, was admitted to hospital numerous times, suffering from the effects of taking the chemical.

She sent desperate messages to her friends telling them she wanted to stop taking the pills but was “psychologically addicted” and knew that feeling her temperature rise meant her fat was burning, jurors heard.

Having driven herself to the Royal Shrewsbury Hospital after feeling unwell, she messaged a friend, saying: “I screwed up big time. Binged/purged all night and took four pills at 4am.

“I took another four when I woke and I started vomiting soon after. I think I am going to die.

“No one is known to survive if they vomit after taking DNP. I am so scared.”

Mr Huynh from Northolt, north-west London, Mr Rebelo and Ms Roberts, both from Gosport, deny two counts each of manslaughter, one count each of supplying an unsafe food, and Ms Roberts faces a single count of money laundering.